Touch sensitive apparatus with improved spatial resolution

ABSTRACT

A touch-sensitive apparatus comprising a panel defining a touch surface; a first set of opposite and essentially parallel rows of components, and a second set of opposite and essentially parallel rows of components. The second set of opposite and parallel rows being essentially orthogonal to the first set of opposite and parallel rows. The components include emitters and detectors, each emitter being operable for propagating an energy beam across the touch surface inside the panel, and each detector being operable for detecting transmitted energy from at least one emitter. Two of the rows of the first and second set are interleaved rows each having an interleaved distribution of emitters and detectors, and the further two rows of the first and second set are base rows each having a distribution of components comprising at least 70% emitters or detectors.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of Swedish patent applicationNo. 1351390-8, filed on Nov. 22, 2013.

FIELD OF THE INVENTION

The present invention relates to a touch sensitive apparatus thatoperates by propagating energy beams across a touch surface inside apanel.

BACKGROUND OF THE INVENTION

This type of touch-sensitive apparatus is known in the art. It may beimplemented to operate by transmitting light inside a solid lighttransmissive panel, which defines two parallel boundary surfacesconnected by a peripheral edge surface. Light generated by a pluralityof emitters is coupled into the panel so as to propagate by totalinternal reflection (TIR) between the boundary surfaces to a pluralityof detectors. The light thereby defines propagation paths across thepanel, between pairs of emitters and detectors. The emitters anddetectors are arranged such that the propagation paths define a grid onthe panel. An object that touches one of the boundary surfaces (“thetouch surface”) will attenuate (“frustrate”) the light on one or morepropagation paths and cause a change in the light received by one ormore of the detectors. The location (coordinates), shape or area of theobject may be determined by analyzing the received light at thedetectors. This type of apparatus has an ability to detect pluralobjects in simultaneous contact with the touch surface, known as“multi-touch” in the art.

In one configuration, e.g. disclosed in U.S. Pat. Nos. 3,673,327,4,254,333 and US2006/0114237, the emitters and detectors are arranged inrows on opposite ends of the panel, and the light is propagated betweenopposite pairs of emitters and detectors so as to define a rectangulargrid of propagation paths.

As an alternative, U.S. Pat. No. 7,432,893 proposes the use of a fewlarge emitters arranged at the corners of the panel, or centrally oneach end of the panel, to inject diverging light beams (“fan beams”)into the panel for receipt by arrays of detectors along all ends of thepanel. This configuration may enable an increased spatial resolution fora given number of emitters and detectors, by increasing the density ofthe grid of propagation paths. The spatial resolution indicates thesmallest object that can be detected by the touch-sensitive apparatus ata given location on the touch surface.

In an alternative configuration, e.g. disclosed in WO2009/077962,US2011/0234537, US2011/0157096, rows of regularly spaced fan beamemitters and detectors, respectively, are arranged on opposite ends ofthe panel to define a dense grid of propagation paths across the touchsurface.

WO2010/064983 discloses further alternative configurations. In oneconfiguration, which is intended to improve the uniformity of the gridof propagation paths, fan beam emitters and detectors are alternatedwith equal spacing around the periphery of the touch surface. In anotherconfiguration, which is intended to reduce interference phenomena thatmay occur when different emitters concurrently inject light of the samewavelength into the panel, fan beam emitters and detectors are arrangedwith randomized spacing around the periphery of the touch surface.

In this type of touch-sensitive apparatus, there is a continued desireto improve the spatial resolution with respect to the uniformity of thespatial resolution across the touch surface or the minimum detectableobject size at a given position on the touch surface.

The touch-sensitive technology is further incorporated into consumerproducts which face challenges such as cost reduction to be competitiveproducts. There is thus desire to reduce cost without endangering theuser experience. The components of the touch-sensitive apparatus mightalso be exposed to disturbances such as ambient noise and noise from theapparatus itself. It is an ongoing desire to reduce the impact ofdisturbances to the components.

SUMMARY OF THE INVENTION

Tl is an objective of the invention to at least partly overcome one ormore limitations of the prior art.

Another objective is to enable an improved spatial resolution for agiven number of electro-optical components in a touch-sensitiveapparatus that operates by propagating energy beams across a touchsurface inside a panel.

A further objective is to provide an apparatus at a reduced cost withoutinfluencing the user experience.

A still further objective is to provide an apparatus that is lesssensitive to disturbances than some prior apparatuses.

One or more of these objectives, as well as further objectives that mayappear from the description below, are at least partly achieved by meansof a touch-sensitive apparatus according to the independent claim,embodiments thereof being defined by the dependent claims.

One aspect of the invention is a touch-sensitive apparatus whichcomprises a panel defining a touch surface; a first set of opposite andessentially parallel rows of components, and a second set of oppositeand essentially parallel rows of components.

The second set of opposite and parallel rows is essentially orthogonalto the first set of opposite and parallel rows. The components includeemitters and detectors, each emitter being operable for propagating anenergy beam across the touch surface inside the panel, and each detectorbeing operable for detecting transmitted energy from at least oneemitter, Two of the rows of the first and second set are interleavedrows each having an interleaved distribution of emitters and detectors,and the further two rows of the first and second set are base rows eachhaving a distribution of components comprising at least 70% emitters ordetectors.

This aspect is based on the insight that the configurations of prior artsolutions, which propagate diverging energy beams inside a panel andhave alternating components of emitters and detectors in opposite rows,will result in a convergence of the propagation paths, typically towardsthe center line between the opposite rows. Thereby, the grid ofpropagation paths will exhibit increased spatial gaps withoutpropagation paths, or angular gaps without propagation paths in largeangular intervals, which is equal to a locally reduced spatialresolution and/or accuracy. A spatial gap is an area between propagationpaths exhibiting no propagation paths. Also, prior art solutions havingan “L-shaped” distribution of components such that two adjacentorthogonal rows comprise the same type of component will result in gapswithout propagation paths or without propagation paths in large angularintervals. To overcome these drawbacks, the first aspect applies thedesign rule that the apparatus comprises four rows of components,wherein two rows arc interleaved rows and the other two rows each has adistribution of components comprising at least 70% emitters ordetectors. By applying this design rule, the number of propagation pathswith different angles may be increased and the propagation paths may bemore evenly distributed over the touch surface. By proper choice andarrangement of components, the first aspect thus provides an improveddistribution of detection lines with different angles over the touchsurface for a given number of components, compared to conventionalarrangements of components. Thus, the spatial resolution and/or accuracyof the touch surface can be increased, or, the spatial resolution and/oraccuracy can be essentially maintained with a reduced number ofcomponents. A reduced number of components might imply a reduced costfor the apparatus.

A detection line can be defined by a distance from a centre point of thetouch surface, and an angle from e.g. a horizontal line through thecentre point. To obtain a certain spatial resolution and accuracy, it isdesired that each point on the touch surface shall have a certain numberof detection lines within a distance to the point, and with adistribution of angles for the detection lines. According to oneembodiment, each point on the touch surface shall have detection lineswith an angle of less than 20°, preferably less than 10°, in between theangles between detection lines within a distance to the point. Thedistance may e.g. be an approximated radius of a fingerpalm.

The components may be arranged in connection with one or several printedcircuit boards (PCBs), and connected to a plurality of distributedprocessors on the PCBs. For example, a certain number of components maybe connected to the same processor. It may be desired to connect onlyone type of component to the same processor, as it may be an easierimplemented solution. For example, signals from the same component typeshould be treated in the same way by the processor. Further, by havingseparate processors for different component types, the influence of theemitters to the detectors may be reduced. Base rows with at least 70% ofone type of component might thus be easier to implement than rows with amore even distribution of components.

According to one embodiment, the interleaved rows constitute the firstset of opposite and parallel rows.

According to another embodiment, the interleaved rows constitute one rowof the first set of opposite and parallel rows, and one row of thesecond set of opposite and parallel rows.

According to one embodiment, the base rows comprises one row with Xnumbers of emitters and one row with Y numbers of detectors, wherein Xis different from Y. Thus, the number of emitters in one base row may begreater than the number of detectors in the other base row. Or, thenumber of emitters in the one base row may be less than the number ofdetectors in the other base row.

According to one embodiment, one of the base rows has a distribution ofcomponents comprising at least 70% emitters and the other base row has adistribution of components comprising at least 70% detectors. Thus, oneof the base rows has a majority of components being emitters, and theother base row has a majority of components being detectors. Therebymore detection lines can be obtained, whereby size of spatial and/orangular gaps, e.g. around the centre line C, in the grid of propagationpaths can be reduced.

According to a further embodiment, the base rows comprise one row withonly emitters and one row with only detectors. The components of theapparatus may be sensitive to disturbances. The detectors are to detectthe energy propagating in the panel, and the detected energy might be ofa small quantity compared to disturbances e.g. from the emitters orambient light or noise. By having a base row with almost only detectorsthe risk that the detected energy, detected with the detectors, becomesdisturbed by the emitters is reduced as the emitters are located moredistant from the detectors than before.

According to one embodiment, at least one of the base rows comprises atleast 80% emitters or detectors, more preferably at least 90% emittersor detectors.

According to one embodiment, at least one of the base rows has a randomdistribution of emitters and/or detectors.

According to one embodiment, “interleaved distribution” is defined by aconsecutive, non-overlapping distribution of alternating blocks withcomponents being either only emitters or only detectors, wherein eachblock B comprises a maximum of two or three components. Thus, anyadjacent blocks have different types of components. The type of“interleaved distribution” can be varied. According to one embodiment,the interleaved distribution is of a type single interleaved, whereineach block B comprises only one component. According to anotherembodiment, the interleaved distribution is of a type multipleinterleaved, wherein each block B comprises a same multiple ofcomponents. According to a further embodiment, the interleaveddistribution is of a type semi-interleaved, wherein blocks with the sametype of components has the same number of components, and wherein thenumber of emitters in a block B is not the same as the number ofdetectors in another block B. According to a still further embodiment,the interleaved distribution is of a type irregular-interleaved, whereinthe number of components in each block B is irregularly chosen. Forexample, the number of components in each block B may be randomlychosen.

According to one embodiment, each emitter is being operable forpropagating a diverging beam. According to a further embodiment, eachemitter is being operable for propagating a diverging beam with a beamdiverging angle α from ±45° to ±90° from a normal of a beam directionsurface of the emitter, the beam diverging angle α being parallel to thetouch surface. For example, the diverging angle may be ±45°, ±60°, ±75°or ±90°.

According to one embodiment, the components are electro-opticalcomponents that are configured to generate radiation and/or energy anddetect radiation and/or energy, respectively.

According to one embodiment, each detector is being operable fordetecting transmitted energy from at least two emitters. According toone embodiment, each detector is configured to receive energy within arange of angles of incidence. In one implementation, each emitter isconfigured to generate radiation and is optically coupled to the panelso as to propagate a diverging beam of radiation across the touchsurface by internal reflections inside the panel, and wherein eachdetector is configured to detect radiation and is optically coupled tothe panel so as to detect transmitted radiation from the at least twoemitters.

According to one embodiment, said first set of rows of components andsaid second set of rows of components define a perimeter ofnon-overlapping and consecutive components around the touch surface.According to a further embodiment, the touch surface has a rectangularform, and each opposite and parallel row of components of the first setis arranged along one short side of the touch surface, and wherein eachopposite and parallel row of components of the second set is arrangedalong one long side of the touch surface.

According to one embodiment, each row comprises at least 20 components,and preferably at least 30 components.

Preferred embodiments are set forth in the dependent claims and in thedetailed description.

SHORT DESCRIPTION OF THE APPENDED DRAWINGS

Below the invention win be described in detail with reference to theappended figures, of which:

FIGS. 1A-1B are section and top plan views of an optical touch-sensitiveapparatus.

FIG. 2 is a 3D plot of an attenuation pattern generated based on energysignals from an optical touch-sensitive apparatus.

FIG. 3A is a top plan view of a grid of detection lines in a prior artapparatus for one type of arrangement with opposite and parallel rowswith interleaved emitters and detectors.

FIG. 3B is a top plan view of a grid of detection lines in an apparatuswhich is designed in accordance with embodiments of the invention.

FIG. 4A is a top plan view of a grid of detection lines in a prior artapparatus with an arrangement with orthogonal rows with interleavedemitters and detectors.

FIG. 4B is a top plan view of a grid of detection lines in an apparatuswhich is designed in accordance with embodiments of the invention.

FIGS. 5-7 are top plan views of grids of detection lines in an apparatuswhich is designed in accordance with embodiments of the invention.

FIGS. 8A-8C are illustrating different interleaved distributionsaccording to some embodiments.

FIG. 9 is illustrating a beam diverging angle u from an emitter.

FIG. 10 is illustrating detection lines within a certain distance to apoint on a touch surface.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In the following, examples of the present invention will be given inrelation to a touch-sensitive apparatus designed to operate by lighttransmission. Throughout the description, the same reference numeralsare used to identify corresponding elements.

FIGS. 1A-1B illustrates an example embodiment of a touch-sensitiveapparatus 100 that is based on the concept of FTIR (Frustrated TotalInternal Reflection). The apparatus 100 operates by transmitting lightinside a panel L from light emitters 2 to light sensors or detectors 3,so as to illuminate a touch surface 4 from within the panel 1. The panel1 is made of solid material in one or more layers and may have anyshape. The panel 1 defines an internal radiation propagation channel, inwhich light propagates by internal reflections. In the example of FIG.1, the propagation channel is defined between the boundary surfaces 5, 6of the panel 1, where the top surface 5 allows the propagating light tointeract with touching objects 7 and thereby defines the touch surface4. This is achieved by injecting the light into the panel 1 such thatthe light is reflected by total internal reflection (TIR) in the touchsurface 4 as it propagates through the panel 1. The light may bereflected by TIR in the bottom surface 6 or against a reflective coatingthereon. It is also conceivable that the propagation channel is spacedfrom the bottom surface 6, e.g. if the panel comprises multiple layersof different materials. The apparatus 100 may be designed to be overlaidon or integrated into a display device or monitor (not shown).

The apparatus 100 allows an object 7 that is brought into close vicinityof, or in contact with, the touch surface 4 to interact with thepropagating light at the point of touch. In this interaction, part ofthe light may be scattered by the object 7, part of the light may beabsorbed by the object 7, and part of the light may continue topropagate in its original direction across the panel 1. Thus, thetouching object 7 causes a local frustration of the total internalreflection, which leads to a decrease in the energy (or equivalently,the power or intensity) of the transmitted light, as indicated by thethinned lines ‘T’ downstream of the touching objects 7 in FIG. 1A.

The emitters 2 are distributed along the perimeter of the touch surface4 to generate a corresponding number of light sheets inside the panel 1.Each light sheet is formed as a beam of light that expands (as a “fanbeam”) in the plane of the panel 1 while propagating in the panel 1 froma respective incoupling region/point on the panel 1. The detectors J aredistributed along the perimeter of the touch surface 4 to receive thelight from the emitters 2 at a number of spaced-apart outcouplingregions/points on the panel 1. It should be understood that theincoupling and outcoupling regions/points merely refer to the positionswhere the beams enter and leave, respectively, the panel 1. The lightfrom each emitter 2 will propagate inside the panel 1 to a number ofdifferent detectors 3 on a plurality of light propagation paths D. Evenif the light propagation paths D correspond to light that propagates byinternal reflections inside the panel 1, the light propagation paths Dmay conceptually be represented as “detection lines” that extend acrossthe touch surface 4 between pairs of emitters 2 and detectors 3, asshown in FIG. 1B. Thereby, the emitters 2 and detectors 3 collectivelydefine a grid of detection lines D (“detection grid”) on the touchsurface 4. The spacing of detection lines in the detection grid maydefine the spatial resolution of the apparatus 100, i.e. the smallestobject that can be detected on the touch surface 4.

The detectors 3 collectively provide an output signal, which is receivedand sampled by a signal processor 10. The output signal contains anumber of sub-signals, also denoted “projection signals”, eachrepresenting the energy of light emitted by a certain light emitter 2and received by a certain light detector 3. Depending on implementation,the signal processor 10 may need to process the output signal forseparation of the individual projection signals. The projection signalsrepresent the received energy, intensity or power of light received bythe detectors 3 on the individual detection lines D. Whenever an objecttouches a detection line, the received energy on this detection line isdecreased or “attenuated”.

The signal processor 10 may be configured to process the projectionsignals so as to determine a property of the touching objects, such as aposition (e.g. in the x. y coordinate system shown in FIG. 1B), a shape,or an area. This determination may involve a straight-forwardtriangulation based on the attenuated detection lines, e.g. as disclosedin U.S. Pat. No. 7,432,893 and WO2010/015408, or a more advancedprocessing to recreate a distribution of attenuation values (forsimplicity, referred to as an “attenuation pattern”) across the touchsurface 1, where each attenuation value represents a local degree oflight attenuation. An example of such an attenuation pattern is given inthe 3D plot of FIG. 2. The attenuation pattern may be further processedby the signal processor 10 or by a separate device (not shown) fordetermination of a position, shape or area of touching objects. Theattenuation pattern may be generated e.g. by any available algorithm forimage reconstruction based on projection signal values, includingtomographic reconstruction methods such as Filtered Back Projection,FFT-based algorithms, ART (Algebraic Reconstruction Technique), SART(Simultaneous Algebraic Reconstruction Technique), etc. Alternatively,the attenuation pattern may be generated by adapting one or more basisfunctions and/or by statistical methods such as Bayesian inversion.Examples of such reconstruction functions designed for use in touchdetermination arc found in WO2009/077962, WO2011/049511, WO2011/139213,WO2012/050510 and US2014/0300572, all of which are incorporated hereinby reference. Conventional image reconstruction techniques are found inthe mathematical literature, e.g. “The Mathematics of ComputerizedTomography” by Natterer, and “Principles of Computerized TomographicImaging” by Kak and Slaney.

In the illustrated example, the apparatus 100 also includes a controller12 which is connected to selectively control the activation of theemitters 2 and, possibly, the readout of data from the detectors 3.Depending on implementation, the emitters 2 and/or detectors 3 may beactivated in sequence or concurrently, e.g. as disclosed inWO2010/064983. The signal processor 10 and the controller 12 may beconfigured as separate units, or they may be incorporated in a singleunit. One or both of the signal processor 10 and the controller 12 maybe at least partially implemented by software executed by a processingunit 14.

It is to be understood that FIG. 1 merely illustrates one example of atouch-sensitive apparatus. For example, instead of injecting anddetecting light via the edge surface that connects the boundary surfaces5, 6, light may be coupled into and/or out of the panel 1 via the topand/or bottom surfaces 5, 6, e.g. by the use of dedicated couplingelements attached to the panel 1. It is also conceivable that the lightis coupled into and out of the panel 1 through different portions of thepanel, e.g. via the boundary surface 5 and the boundary surface 6,respectively. Examples of alternative FTIR-based touch systems are e.g.disclosed in U.S. Pat. No. 7,432,893, WO2010/046539, WO2012105893 andWO2013/089622, which are all incorporated herein by this reference.

Embodiments of the invention apply specific design rules for theordering of emitters 2 and detectors 3 along the perimeter of the touchsurface 4 to achieve desired properties of the detection grid on thetouch surface 4, as will be further explained in relation to the topplan views in FIGS. 3-7. Each of the figures illustrates a grid ofdetection lines that are defined between horizontal rows 22A, 22B andvertical rows 20A, 20B of emitters 2\filled circles) and detectors 3(filled squares) on ends or sides of a touch surface. The components 2,3 in any row are consecutively arranged in a non-overlapping way. Forease of presentation, the panel 1 and its touch surface 4 has beenomitted in FIGS. 3-7.

FIG. 3A is illustrating a conventional fan beam arrangement, whereinemitters 2 and detectors 3 arc arranged in an alternating fashion withequal spacing in two rows along opposite ends of the touch surface 4,herein denoted “first interleaved arrangement”. The first interleavedarrangement results in a symmetric detection grid, and each intersectionpoint on the center line “C” between the rows 22A, 22B contains a largenumber of detection lines. As shown, this results in “gaps” in thedetection grid.

FIG. 3B is illustrating two base rows 22A, 22B according to oneembodiment, where the base rows 22A, 22B are arranged in two rows alongopposite ends of the touch surface 4. One base row 22A comprises onlyemitters 2 and the other base row 22B comprises only detectors 3 withequal spacing. The number of components, and size of spacing is the sameas in FIG. 3A. The arrangement with base rows with one row 22A with onlyemitters 2 and one row 22B with only detectors 3 results in a symmetricdetection grid, with “gaps” in the detection grid that are smaller thanthe “gaps” in the detection grid of FIG. 3A. Thus, the arrangement inFIG. 3B provides an increased uniformity and reduced spacing ofpropagation paths compared to the example shown in FIG. 3A.

FIG. 4A is illustrating another conventional fan beam arrangementwherein emitters 2 and detectors 3 are arranged in blocks B in analternating fashion with equal spacing in two rows 20A, 22B alongorthogonal ends of the touch surface 4, herein denoted “secondinterleaved arrangement”. Each block B comprises one emitter 2 ordetector 3. The second interleaved arrangement results in a symmetricdetection grid.

Another conventional fan beam arrangement that is not illustrated in anyfigure is the “L-shaped” arrangement where two rows are arranged withthe same type of component 2, 3 along orthogonal ends of a touch surface4. Thus, two orthogonal rows are arranged with detectors 3, and theother two orthogonal rows are arranged with emitters 2. As understood bythe: skilled person, the orthogonal rows with the same type of componentdo not create any detection lines that can be detected in between therows, and a lot of gaps with no propagation paths in large angularranges are obtained. However, it may be advantageous to have rows withonly one kind of component, or a majority of only one component, as itis an arrangement that may be easier to implement.

FIG. 4B is illustrating one base row 22B and one interleaved row 20Aarranged along orthogonal ends of the touch surface 4. The base row 22Bcomprises only detectors 3 with equal spacing, and the interleaved row20A comprises emitters 2 and detectors 3 arranged in an alternatingfashion with equal spacing. The interleaved row 20A is subdivided intoblocks B. here with one emitter 2 or detector 3 in each block B. Thearrangement results in a detection grid with essentially the same numberof detections lines as in the detection grid in FIG. 4A. The detectionlines in FIG. 4B are however offset compared to the detection lines inFIG. 4A. Compared to the embodiment in FIG. 4A, the arrangement in FIG.4B provides new detection lines from emitters 2 in the interleaved row20A to the detectors 3 in the base row 22B, but loses detection linesfrom emitters 2 in the base row to detectors 3 in the interleaved row20A. Compared to the “L-shaped” arrangement (not shown), the arrangementin FIG. 4B provides more evenly distributed detection lines on the touchsurface 4, contributing to an improved spatial resolution. Compared tothe arrangement of FIG. 4A the arrangement of FIG. 4B may create moregaps in the detection grid. However, when combined with two or more rowsof components along the other opposite ends of the touch surface 4 thearrangement of FIG. 4B may create fewer and/or smaller gaps than anarrangement of four interleaved rows, as will be discussed withreference to FIGS. 5 and 6.

The embodiments shown in FIGS. 3B and 4B have been illustrated withcomponents arranged along only two ends of the touch surface 4 toillustrate genera] benefits with the embodiments arranged according tocertain design rules. The embodiments in FIGS. 3B and 4B can be combinedto benefit from a resulting symmetric and enhanced detection gridobtained when four ends or the touch surface 4 each is aligned with arow 20A, 20B, 22A, 22B of components 3, 4. Two of the rows 20A, 20B,22A, 22B are interleaved rows each having an interleaved distribution ofemitters 2 and detectors 3, and the further two rows 20A, 208, 22A, 22Bare base rows each having a distribution of components 2, 3 comprisingat least 70% emitters 2 or detectors 3.

The above-described general design principle for the touch-sensitiveapparatus makes it possible to achieve an increased spatial resolutionand/or accuracy of the touch-sensitive apparatus without increasing thenumber of components per unit length. Thus, embodiments of the inventionmake it possible to attain a higher spatial resolution and/or accuracyfor a given number of electro-optical components (emitters anddetectors). The resolution is improved with a denser detection grid andthe accuracy is improved when the detection lines are distributed over alarge angular range. To obtain a certain spatial resolution andaccuracy, it is desired that each point on the touch surface shall havea certain number of detection lines within a certain distance d to thatpoint, and with a distribution of angles for the detection lines. FIG.10 illustrates an enlarged view of a point P on the touch surface with anumber of nearby detection lines D within the certain distance d to thepoint. The detection lines are angularly distributed. There are howeverangular gaps β between the detection lines, where there are no detectionlines. These angular gaps β reduces the accuracy. The angular gaps βbetween the detection lines should therefore be small, so each point onthe touch surface may have detection lines with angular gaps of lessthan 20°, preferably less than 10° or 5°, between the detection lineswithin a certain distance d to the point when the touch apparatus isbeing operated. The distance d may e.g. be an approximated radius of afingerpalm.

In FIG. 5 an embodiment is illustrated comprising a first set ofopposite and essentially parallel rows 20A, 20B of components 2, 3 and asecond set of opposite and essentially parallel rows 22A, 22B ofcomponents 2, 3. The second set of opposite and parallel rows 22A, 22Bis essentially orthogonal to the first set of opposite and parallel rows20A, 20B. In this embodiment the interleaved rows constitute the firstset of opposite and parallel rows 20A, 20B. The base rows thenconstitute the second set of opposite and parallel rows 22A, 22B. Onebase row 22A comprises only emitters 2 and thus has a distribution ofcomponents 2, 3 of 100% emitters 2. The other base row 22B comprisesonly detectors 3 and thus has a distribution of components 2, 3 of 100%detectors 3. The base rows 22A, 22B may have another distribution ofcomponents 2, 3, however at least 70% emitters 2 or detectors 3 each.The interleaved rows 20A, 20B are of the type single interleaved,wherein each block B comprises only one component 2, 3. The touchsurface 4 here has a rectangular form, and each of the rows 20A, 20B ofcomponents 2, 3 of the first set is arranged along one short side of thetouch surface 4, and each row 22A, 22B of components 2, 3 of the secondset is arranged along one long side of the touch surface 4. An apparatuswith an arrangement as illustrated in FIG. 5 may thus have the drawbackof larger gaps in the detection grid as illustrated in FIG. 4B, but willalso have the benefits of the detection grid as illustrated in FIG. 3Band explained in the text thereto. The combination of the arrangementsof FIGS. 3B and 4B gives a detection grid with generally smaller spatialgaps and smaller angular gaps, as compared to a combination of thearrangements of FIGS. 3A and 4A with four interleaved rows at four endsof a touch surface 4.

In FIG. 6 a further embodiment is illustrated comprising a first set anda second set of components in similarity with the embodiment shown inFIG. 5. However, in this embodiment the interleaved rows constitute onerow 20B of the first set of opposite and parallel rows 20A, 20B, and onerow 22A of the second set of opposite and parallel rows 22A, 22B. Thebase rows then constitute the other row 20A of the first set of oppositeand parallel rows 20A, 20B, and the other row 22B of the second set ofopposite and parallel rows 22A, 22B. One base row 20A comprises onlyemitters 2 and thus bas a distribution of components 2, 3 of 100%emitters 2. The other base row 22B comprises only detectors 3 and thushas a distribution of components 2, 3 of 100% detectors 3. The base rows20A, 22B may have another distribution of components 2, 3, however atleast 70% emitters 2 or detectors 3 each. The interleaved rows 20B, 22Aare of the type single interleaved, wherein each block B comprises onlyone component 2, 3. The touch surface 4 here has a rectangular form, andin similarity with the embodiment in FIG. 5, each of the rows 20A, 20Bof components 2, 3 of the first set is arranged along one short side ofthe touch surface 4, and each row 22A. 22B of components 2, 3 of thesecond set is arranged along one long side of the touch surface 4. Thisarrangement of components also gives a detection grid with generallysmaller spatial gaps and smaller angular gaps, as compared to thecombination of the arrangements of FIGS. 3A and 4A with four interleavedrows at four ends of a touch surface 4.

In FIG. 7 a still further embodiment is illustrated comprising a firstset and a second set of components in similarity with the embodimentsshown in FIGS. 5 and 6. Also, as in the embodiment shown in FIG. 5, theinterleaved rows constitute the first set of opposite and parallel rows20A, 20B. The base rows then constitute the second set of opposite andparallel rows 22A, 22B. One base row 22A comprises a number of 17emitters 2 out of 20 components, thus more than 70% of emitters 2. Theother base row 22B comprises a number of 17 detectors 3 out of 20components in the base row 22B, thus more than 70% of detectors 3. Thecomponents 2, 3 in the interleaved rows 20A, 20B are subdivided intoblocks B. The interleaved rows 20A, 20B are here of the typeirregular-interleaved, wherein the numbers of components 2, 3 in eachblock B is irregularly chosen. The number of components 2, 3, may e.g.be chosen according to an optimization scheme, depending e.g. on thetotal available number of components 2, 3, size of touch surface,desired resolution of touch surface etc. According to one embodiment,the number of components 2, 3 in each block B may be randomly chosen.Each block B comprises one, two or three components 2, 3 of either thetype emitter 2 or detector 3. Thus, each block B contains only emitters2 or detectors 3. Adjacent blocks B have a different type of component2, 3. As can be seen in the FIG. 7, the interleaved row 20A to the leftin the Figure has a plurality of blocks B with only one emitter 2 ordetector 3, and one block B with two detectors 3 and one block B withtwo emitters 2. The interleaved row 20B to the light in the Figure has aplurality of blocks B with only one emitter 2 or detector 3, and twoblocks B with two detectors 3 and two blocks B with two emitters 2. Insimilarity with FIGS. 5 and 6, the touch surface 4 has a rectangularform, and each of the rows 20A, 20B of components 2, 3 of the first setis arranged along one short side of the touch surface 4, and each row22A, 22B of components 2, 3 of the second set is arranged along one Jongside of the touch surface 4. Other examples of arrangements ofcomponents within a row are found in WO2013176614 and WO2013176613,which are incorporated herein by reference.

When the apparatus is provided with communicating possibilities, e.g.integrated into a laptop or smartphone, disturbances such aselectrostatic discharge (ESD) from antennas might disturb the detectedenergy. This problem increases when the detectors 2 are located close tothe antennas. In the embodiments described, one of the ends of the touchsurface 4 will have a base row with less number of detectors 3, or nodetectors 3 at all. This base row may be arranged to be closest to theantenna/antennas, e.g. on the most distal end of the touch surface 4.For example, this distal end may be dose to an upper edge of a laptopcomprising a display with touch-sensitive capabilities as initiallydescribed. Also, this distal end may become more exposed to otherambient disturbances, making it more suitable for emitters 3 that may beless sensitive to disturbances than detectors 2.

FIGS. 8A-8C are illustrating examples of interleaved distributions ofthe interleaved rows according to some embodiments. The principles ofthese interleaved distributions can be used to arrange the components inthe interleaved rows in any of the herein described embodiments. InFIGS. 8A-8C only some components 2, 3 are illustrated to show theprinciple, but it is understood that the number of component can beincreased or decreased as desired to suit a certain design and/or sizeof touch surface 4. FIGS. 8A-8B are illustrating interleaveddistributions of the type multiple interleaved, wherein each block Bcomprises the same multiple of components. In the FIG. 8A each block Bcomprises two emitters 2 only or two detectors 3 only. The blocks B arethen alternatingly arranged such that two adjacent blocks B do notcomprise the same type of components 2, 3. In the FIG. 8B each block Bcomprises three emitters 2 only or three detectors 3 only. The blocks Bare then alternatingly arranged such that two adjacent blocks B do notcomprise the same type of components 2, 3. FIG. 8C is illustrating aninterleaved distribution of a type semi-interleaved, wherein blocks Bwith the same type of components 2, 3 has the same number of components2, 3, and wherein the number of emitters 2 in a block B is not the sameas the number of detectors 3 in another block B. In FIG. 8C the numberof detectors 3 in each block B with detectors is two, and the number ofemitters 2 in each block B with only emitters is one. This example isshown to illustrate the principle, and many alternatives of asemi-interleaved distribution are possible. For example, the number ofdetectors 3 in each block B with detectors may be one or three. Further,the number of emitters 2 in each block B with emitters may be two orthree.

In the above-described embodiments, all components 2, 3 are arrangedwith equi-distant center-to-center spacing within each row. Such adesign may facilitate manufacture of the touch-sensitive apparatus.However, it is conceivable to achieve further improvements in terms ofuniformity and/or gap size of the detection grid, by varying the spacingof the components 2, 3 within one or both of the interleaved rows. Forexample, the spacing between different blocks may be varied so that theblocks are arranged with alternating short/long spacing. Alternatively,the blocks in the interleaved rows may be arranged spatially separatedfrom each other, which might enhance the spatial resolution. Spatiallyseparated blocks may be defined by having a center-to-center spacingbetween adjacent components in different blocks that is larger than acenter-to-center spacing between adjacent components within each blockB. The components in each block may also be arranged spatially separatedfrom each other, which also might enhance the spatial resolution.Spatially separated components in a block may he defined by having acenter-to-center spacing between the adjacent components within theblock B that is larger than a center-to-center spacing between adjacentcomponents in different blocks B. Examples of spacings between adjacentblocks are found in WO2013/176615, which is incorporated herein byreference.

It should be noted that certain image reconstruction techniques, e.g.tomographic techniques, may require (or benefit from) a uniform angulardistribution of detection lines on the touch surface 4, i.e. that thedetection lines that intersect a respective reconstruction cell on thetouch surface 4 are evenly distributed in the angular direction, andpossibly also that the number of detection lines is approximately thesame in all reconstruction cells. A reconstruction cell denotes asub-area of the touch surface 4 which is assigned an attenuation valueby the reconstruction process. It has been revealed that the embodimentsdescribed herein provide a detection grid with detection lines with amix of angles beneficial when reconstructing an image of the touchsurface.

As used herein, “horizontal”, “vertical”, “left” and “right” merelyrefer to directions on the drawings and does not imply any particularpositioning of the panel 1.

According to one embodiment, the base rows may comprise one row with Xnumber of emitters 2 and one row with Y number of detectors 3, wherein Xis different from Y. Thus, a different number of components 2, 3 of eachtype can be had on each base row. In the above described embodiments,opposite rows have been illustrated with an equal number of components.However, the number of components on each side may be different.

As illustrated in FIG. 9, light from each emitter 2 may be propagatinginside the panel 1 as a diverging beam with a beam diverging angle αfrom ±45° to ±90° from a normal vector N of a beam direction surface 15of the emitter 2. The direction of the beam direction surface 15determines the overall direction of the diverging beam. Here, the beamdirection surface 15 is perpendicular to the touch surface 4, and thebeam diverging angle α is parallel to the touch surface 4. For example,the diverging angle may be ±45°, ±60°, ±75° or ±90°. The diverging beammay also diverge between the boundary surfaces 5, 6 of the panel 1,which is not illustrated in the figure.

Symmetry artifact may arise close to the edges of the touch surface 4,thus leaving gaps in the detection grid without propagation paths. Thesegaps may be reduced by arranging one or several extra components 2, 3,e.g. emitters 2, in any of the rows such that light from the emitter oremitters 2 strikes the previous gap in the detection grid. For example,in the arrangement in FIG. 4B one or several extra emitters 2 may bearranged in the base row between detectors 3 and be arranged to projecta beam of light in the gap in the detection grid.

The present invention is not limited to the above-described embodiments.Various alternatives, modifications and equivalents may be used. Forexample, the touch surface 4 may have a rectangular form with equallysized ends. Therefore, the above embodiments should not be taken aslimiting the scope of the invention, which is defined by the appendingclaims.

1. A touch-sensitive apparatus, comprising: a panel (1) defining a touchsurface (4); and a first set of opposite and essentially parallel rows(20A, 20B) of components (2, 3); a second set of opposite andessentially parallel rows (22A, 22B) of components (2, 3), said secondset of opposite and parallel rows (22A, 22B) being essentiallyorthogonal to the first set of opposite and parallel rows (20A, 20B),wherein the components include emitters (2) and detectors (3), eachemitter (2) being operable for propagating an energy beam across thetouch surface (4) inside the panel (1), and each detector (3) beingoperable for detecting transmitted energy from at least one emitter (2);characterized in that two of the rows (20A, 20B, 22A, 22B) of the firstand second set are interleaved rows each having an interleaveddistribution of emitters (2) and detectors (3), and wherein the furthertwo rows (20A, 20B, 22A, 22B) of the first and second set are base rowseach having a distribution of components (2, 3) comprising at least 70%emitters (2) or detectors (3). 2.-18. (canceled)